There are some 4870 Sapphire cards that did ship with a somewhat faulty BIOS, but you need to know its exact model to know if it was affected or not. I think it was only the 1GB version tho, not sure.
as for your BIOS question, you should update it to the latest stable version and check. Although I believe it's just the boot order you have set up wrong, it could help.

Additionally, I'd like to make public that I got rid of that pesky aaCenter.exe thing that installs with ASUS softweare, and curious, after having the temp bug on a daily basis, I haven't gotten it for a week now...